Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
CA 02814801 2013-04-15
WO 2012/067500
PCT/NL2011/050703
METHOD FOR FORMING GROUND-COVERING LAYER AND THE GROUND-COVERING LAYER
The invention relates to a method for forming a
ground-covering layer. Such a layer can for instance be used to
stabilize or protect a ground against erosion.
Already known from the British patent 2.185.769 is a
method for forming a ground-covering layer wherein a grid of
geotextile is formed. This grid is formed by laving onto each
other and connecting to each other a number of strips of a
geotextile material, wherein a strip is connected in each case
to two adjacent strips at mutually offset locations. When the
thus formed package of mutually connected strips is then placed
on its edge and pulled apart, a grid is created which defines
a number of spaces bounded by the strips. This grid can be placed
on a ground surface and the spaces can then be filled, for
instance with sand, earth or rubble. The known ground-covering
layer is used for instance to stabilize sloping ground surfaces,
such as dike bodies. In a variant of the method according to this
British patent the grid is glued to a base of geotextile after
being folded out, wherein the other side of the base can then
be further covered with a water-impermeable layer of plastic.
A watertight stabilizing layer is thus obtained.
The known method has the drawback of being relatively
complicated and requiring quite a large number of operations.
This is particularly the case when it is the desire to obtain
a grid closed on the underside.
The invention therefore has for its object to provide a
method of the above described type wherein these drawbacks do
not occur, or at least do so to lesser extent. According to the
invention this is achieved with a method comprising the steps
of:
providing a sheet;
forming a number of substantially parallel folds in the
sheet; and
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uroing toward each other and connecting to each other
adjacent folds at different locations, wherein the connections
of each fold to an adjacent fold on the one side are offset
relative to the connections to an adjacent fold on the other side.
By making use of a sheet in which folds can be formed a
grid can be formed in much simpler manner than if use is made
of separate strips. The spaces formed between the folds are
moreover directly closed on the underside by the sheet. A
separate groundsheet need not therefore be connected to the grid.
The method preferably further comprises the step of at
least partially filling spaces formed between the mutually
connected folds with a functional material. This functional
material can be a weighting material, such as sand, earth or
gravel, but could for instance also be a granular, damping or
resilient material such as rubber, polystyrene and the like. The
ground-covering layer can thus be readily adapted to the purpose
for which it is used.
The connections can be formed in simple manner by glueing
the folds locally to each other. It is on the other hand also
possible to form the connections by stitching the folds locally
to each other. When the sheet is manufactured at least partially
from plastic, the connections can also be formed by welding the
folds locally to each other, for Instance by ultrasonic welding.
Although the connections are a significant factor in
stabilizing the ground-covering layer, it may be advantageous
to form these connections over only a part of the height of the
folds. The part of the folds above the connections can then be
used for other functions.
The method can for instance further comprise the step of
cutting through at least some of the folds above the connections.
Separate upright parts are thus formed.
If the sheet is woven and a density is chosen at the
position of at least some of the folds which is lower than between
the folds, after being cut through the upright parts can form
loose fibres which can for instance serve as artificial grass
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blades. This can be achieved by arranging fewer warp or weft
threads (depending on the orientation of the folds) in the woven
material at the position of the folds.
Conversely, it is possible for a second sheet to be laid
over the spaces and connected to the severed parts of the folds.
A larger area of contact is formed with the sheet lying above
by using the severed parts, whereby a strong connection can be
effected. The sheet with the folds and the second sheet lying
thereabove thus form a closed construction, the spaces of which
can be filled with a functional material. This functional
material can for instance be a damping material, such as plastic
granules, whereby a damping mat is obtained.
With a view to obtaining a stable grid, it can be
advantageous for the sheet to be strengthened at the position
of at least some of the folds. In the case of a woven sheet this
can be achieved in simple manner by locally co-weaving relatively
stronger or stiffer warp or weft threads. A non-woven can be
strengthened by arranging strengthening threads or strips
locally thereon.
The sheet can be manufactured at least partially from
natural material. This reduces the environmental impact and the
ground-covering layer can be easily recycled after use.
The sheet between the folds can advantageously be
manufactured at least partially from biodegradable material. Due
to the decomposition of this biodegradable material between the
folds openings are thus formed in the sheet after a period of
time through which for instance vegetation can grow. The
ground-covering layer is thus further secured to the underlying
ground by the vegetation, and a natural whole is eventually
obtained.
The invention further relates to a ground-covering layer
which can be obtained by applying the above described method.
Such a layer comprises according to the invention a sheet with
a number of substantially parallel folds, which folds are
connected at different locations to adjacent folds, wherein the
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connections of each fold to an adjacent fold on the one side are offset
relative to the connections to an adjacent fold on the other side .
The invention also provides a method for forming a ground-
covering layer, comprising the steps of: providing a sheet; forming a
plurality of substantially parallel upstanding folds in the sheet; and
urging toward each other and connecting to each other adjacent folds at
different locations, wherein the connections of each fold to an
adjacent fold on the one side are offset relative to the connections to
an adjacent fold on the other side to form a plurality of pockets with
closed undersides.
Also provided is a ground-covering layer, comprising a sheet with
a plurality of substantially parallel upstanding folds, which folds are
connected at different locations to adjacent folds, wherein the
connections of each fold to an adjacent fold on the one side are offset
relative to the connections to an adjacent fold on the other side to
form a plurality of pockets with closed undersides.
Preferred embodiments of the ground-covering layer according to
the invention form the subject matter of the sub-claims 13 to 22.
The invention is now elucidated on the basis of a number of
embodiments, wherein reference is made to the accompanying drawing in
which corresponding components are designated with the same reference
numerals, and in which:
Fig. 1 to 5 show the different steps of the method for forming a
ground-covering layer according to the invention,
Fig. 6 is a top view of a woven material with locally reduced
density,
Fig. 7 and fig. 8 are perspective views of the woven material of
fig. 6 after folds have been formed therein and these folds have been
cut open,
Fig. 9 is a top view of an alternative embodiment of the ground-
covering layer manufactured from a natural material and formed with
stitching,
Fig. 10 is a side view of yet another embodiment of the ground-
covering layer, wherein the spaces between the folds are closed by a
second sheet, and
Fig. 11 is a perspective view of the ground-covering layer in use
on a ground surface. In the method for forming a ground-covering layer
1 according to the invention use is made of a sheet 2 (fig. 1). This
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sheet 2 can be a woven material, but also a non-woven, and can for
instance be a length with a standard width of 4 m as frequently used in
the carpet and artificial grass industry. Formed in sheet 2 are a
number of parallel folds 3 of substantially equal height h and at a
substantially equal intermediate distance d (fig. 2). Folds 3 can for
instance be formed by guiding the sheet over suitable pleating or
folding rollers. Folds 3 are then fixed by for instance being connected
to each other at two different levels in longitudinal direction (fig.
3) with the forming of longitudinal connections 4. Depending on the
nature of the material used, folds 3 can be connected by glueing,
welding (thermal or ultrasonic), stitching or any other suitable
connecting technique.
The height h and intermediate distance d of folds 3 are adapted
to each other such that they can be urged toward and connected to each
other locally without too much difficulty (fig. 4) . The connections of
each fold to an adjacent fold on the one side are here offset relative
to the connections to an adjacent fold on the other side, so that a
grid is formed. For the purpose of forming the local connections 5 use
is once again made of techniques such as glueing, welding or stitching,
this time in height direction. The pitch s between the corresponding
connections 5 determines together with the intermediate distance d the
final form of the grid formed by folds 3 and of the spaces 6 between
the folds 3 connected locally to each other. The sheet 7 between folds
3 forms a base for spaces 6. When layer 1 has been thus formed, it can
be laid on a ground surface G, after which spaces 6 can be filled with
a stabilizing or weighting material 8 such as sand, earth or rubble or
the like (fig. 5) .
In the shown embodiment sheet 2 is a uniform woven material or a
non-woven. It is however also possible to envisage sheet 2 being
.. strengthened at the position of folds 3, for instance by using stronger
or stiffer warp or weft threads there (depending on the direction of
folds 3 in the woven material).
Conversely, it is also possible to give the woven material a less
dense form, precisely at the position of folds 3, by omitting warp or
.. weft threads there (fig. 6). After forming and fixing of the folds the
remaining weft or warp threads then form pile threads 9 there (fig. 7),
which can be cut through to form blades 10. Folds 3 of sheet 2 can be
pulled for this purpose over a set of knives. Folds 3 can then be urged
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toward each other again locally and connected to each other in order to
form a grid. Connections 5 then of course extend only over the part of
folds 3 lying under the blades. When the woven material is made of
green thread, ground-covering layer 1 in this way acquires the
appearance of an (artificial) grass field. When layer 1 is applied as
stabilizing layer on a loose ground, for instance as verge adjacently
of a road, this results in a more natural appearance. If however spaces
6 are filled with a mixture of sand and rubber granules, the ground-
covering layer could even be used as artificial grass field for sport
or games.
The omission of warp or weft threads at the position of folds 3
is not only important for the purpose of forming blades but also in
respect of the draining properties of layer 1. This is because folds 3
hereby become porous on the upper side so that water can sink through
folds 3 and can thus be discharged.
Sheet 2 can be made of plastic, although the use of natural
materials, such as jute, can also be envisaged (fig. 9). In this case
the connections are formed by stitching with a thread of natural
material. This applies for both the longitudinal connections 4 for
fixation of folds 3 and connections 5 in height direction for the
purpose of forming the grid.
In yet another embodiment of ground-covering layer 1 according to
the invention the folds 3 are likewise cut open after fixing thereof,
but are not used as upright blades for embellishing the appearance of
layer 1. The cut-open upper ends 11 of folds 3, after the spaces 6
therebetween have been filled with a filler material 8, are instead
folded over the filling (fig. 10). A second sheet 12 is then laid over
the thus formed ground-covering layer 1 and attached thereto by being
welded or glued to the upper ends 11 of folds 3. A layer is thus
created with a large number of chambers closed on all sides and bounded
by folds 3, the sheet 7 therebetween functioning as base, and the
second sheet 12. The surface available for the weld or glue connections
13 is considerably enlarged by folding the upper ends 11 of folds 3
away from each other. A granular plastic such as polystyrene granules
can for Instance be used in this case as filler material 8. Ground-
covering layer 1 can then be
applied
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as damping layer, for instance under a sports field or playing field.
As stated, layer 1 can be laid on a ground surface G and then
filled with a weighting stabilizing filler material 8. This filler
material 8 can form part of a dike body 14 formed on layer 1 (fig. 11)
or of a landscaped top layer 15 arranged over ground-covering layer 1.
This figure otherwise further shows how ground-covering layer 1 can be
fixed to ground surface G by means of pins 16.
Instead of arranging a layer of vegetation over ground-covering
layer 1, it is also possible to opt to allow vegetation to grow on
layer 1. Biodegradable materials can for this purpose be incorporated
in sheet 2, particularly the part 7 between folds 3. When these
materials, for instance warp and/or weft threads in the case of a woven
material, decompose, openings are created in layer 1 through which
plants or grass can grow.
The invention thus provides the option of forming in simple
manner in a production line a grid with base which can be used as
ground-covering layer. This layer can function as stabilizing layer and
can counter erosion of the ground surface. The layer can also be used
as playing or sports field, while with a suitable choice of the filler
material an application as damping substrate for playing or sports
fields can also be envisaged. When the layer is formed from a woven
material, the properties of the layer can be varied locally through a
suitable choice of warp and/or weft threads. The strength and stiffness
of the grid can thus be increased, while in addition the water drainage
through the folds - the walls of the grid - can for instance be
enhanced. Plants or grass can eventually grow on the layer by embodying
a part of the layer in biodegradable material.
Although the invention is described above on the basis of a
number of embodiments, it will be apparent that it is not limited
thereto. The invention can be varied in many ways within the scope of
the following claims.
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